About 90% of the dermis of the skin is collagen, which exhibits the functions of supporting the skin structure, providing an environment for cell survival, and retaining moisture. It is known that collagen is lost when the skin is subject to specific exogenous influences, such as ultraviolet-ray exposure, dryness, etc. It has been found that collagen is lost by aging and stress. It has also been found that such exogenous influences and/or aging causes a reduction in the amount of collagen production in skin fibroblast.
The functions of retaining a moderate amount of collagen as well as exhibiting an excellent collagen production ability are important in maintaining healthy skin. Heretofore, substances that promote collagen production have been actively sought (e.g., Japanese Unexamined Patent Publication Nos. 2001-316240 and 2003-278783,A). However, it has not been reported that nucleic acid and its related substances have an action of promoting collagen production.